Machines such as mechanical breakers, drills, and mechanical tampers are examples of percussion tools whose vibrations, if they are not damped, are liable to reach levels that are harmful to the operator or to the supporting machinery. Vibration related problems also exist with other types of machines, for instance with heavy rotary drilling machines, motor saws, brush saws and shearing machines based on rotary or reciprocatory tool movement. Various vibration damping means have been proposed in an endeavour to overcome these problems. However, progressively sharpened standard requirements have meant that the solutions hitherto proposed in this regard fail to ensure that the tool or machine is sufficiently friendly to both workman and machinery.
Various types of spring devices have been used to dampen vibrations, including pneumatic devices, with subsequent undesirable air losses when damping vibrations, and more general elastic materials and steel springs. As an example of these two latter applications in hand-held percussion tools with different drive systems, reference can be made to Patent Specifications 1) EP/SE 0 104 154, 2) SE 226 416 and 3) U.S. Pat. No. 4,111,269. According to Patent Specification 1), handle vibrations are dampened with the aid of a rubber diaphragm. This damping effect is impaired, however, by rotary vibration and frictional forces generated between the outer surface of the machine and the front part thereof. Patent Specification 2) teaches a vibration damping solution which employs the use of a built-in helical spring. However, this solution is also encumbered with disturbing vibration-transmitting friction in the guides. Patent Specification 3) discloses non-linear leaf-spring damping, which is restricted to the furthest rearward handgrip, while balanced handling of the front part of the machine must be achieved in the absence of vibration damping.